The present invention relates to a data-transmitting apparatus having a connecting plug, in which digital data representing various physical or chemical quantities measured by measuring devices is received through the connecting plug, and is transmitted to an external apparatus in the form of a radio message.
In a factory, products are subjected to various inspections. An inspection line is provided in the factory to inspect the products. Measuring devices of various types are arranged along the inspection line. As the products are moved in the inspection line, their physical or chemical quantities are measured by means of the measuring devices. Pieces of data representing the physical or chemical quantities measured by the devices are collected in a host apparatus. The data collected in the host apparatus is used to calculate the quality and yield of the products.
There are various kinds of inspection performed on the products. One of them is the size-measuring of products. When the products have a complicated shape, ten or more dimensional values must be measured of each product. One person may use vernier calipers to measure all these dimensional values. Usually, however, several persons use vernier calipers or similar measuring devices, each person measuring a few dimensional values. This method is preferred since the work efficiency is higher, and the error rate is lower, than when each person measures all dimensional values of the product. Hence, many measuring devices of the same type are required in most cases.
Data representing the values measured by the measuring devices supplied to, through cables, and is collected, in the host apparatus of a data collecting system. The data must be digital, or it cannot be processed in the host apparatus. Recently, a measuring device containing an analog-to-digital (A/D) converter has been put to practical use. The device measures a value of an article. The A/D converter converts the data representing this value to digital data. The digital data is transmitted via cables, from the device to the host apparatus. Since the data signals are digital, they are neither attenuated, nor degraded by noise. Hence, the reduction of the accuracy of the data can be minimized.
In the data collecting system, the measuring devices are connected by relays and cables to the host computer provided within the host apparatus. The cables, which connect the measuring devices to the relays coupled to the host computer, may hinder the persons using the devices in their work, particularly when the measuring devices are verniner calipers, micrometers, or the like. In short, the cables may reduce the work efficiency.
Further, the number of measuring devices which can be connected to one relay is limited. Hence, the more measuring devices, the more relays for supplying the items of data to the host computer. An increase in the number of relays no doubt results in an increase in the size and cost of the data collection system.